Multi-determination of Para red and Sudan dyes in egg by a broad specific antibody based enzyme linked immunosorbent assay

Para red and Sudan dyes (Sudan 1, 2, 3, 4, and Sudan G) have been proven to show the potential carcinogenic effect to human. This study first reported an indirect competitive immunoassay (ELISA) for simultaneous detection of the six red dyes in egg. Two immunogens of Para red were prepared by coupling the deoxidized Para red to carrier protein by using of diazotization method and glutaraldehyde method, respectively. The obtained polyclonal antibodies showed broad specificity toward Para red and the five Sudan dyes with crossreactivity in a range of 26%–108%. After evaluation of different coating antigen/antibody combinations, a heterologous ELISA was developed to simultaneously determine these red dyes in egg. The limits of detection for these analytes were in a range of 0.2–0.6 ng/g depending on the compound. Intra- and inter-assay recoveries from the standards fortified blank samples were in the range of 77.2%–96.0% with coefficients of variation lower than 10.3%.